Power regulators are known per se. They serve to keep a supply voltage and/or supply current within a certain range. A so-called switched mode power supply (SMPS) is arranged for switching a current on and off, typically at a high frequency. A linear regulator is simpler and produces no noise but has a higher power dissipation.
International Patent Application WO 2013/130088 discloses a dual mode voltage regulator having a passive regulator circuit, a switching regulator circuit and a controller circuit. An external select input is arranged for receiving external parameters which can be determined by the controller circuit so as to select one of the regulator circuits. This known regulator has the drawback that it depends on external parameters to select a mode and that the regulator is ineffective if the external parameters are not supplied.
U.S. Pat. No. 7,710,089 discloses a power regulator which automatically configures to work in either SPMS mode or linear mode. This known regulator has a dedicated pin which may be connected to a boot capacitor or to ground. An auto-detect circuit detects in which way the dedicated pin is connected. This known regulator has the disadvantage that a dedicated pin must be connected in a certain way to select a mode.
U.S. Pat. No. 8,067,925 discloses a power regulator circuit which can be operated in switching mode under high load current load conditions and in linear mode under light load current conditions. To this end, a detection circuit detects the stationary output current and/or voltage and controls the switching between the two modes. This known regulator has the disadvantage that properties of the regulator circuit itself are not taken into account when selecting a mode.
U.S. Pat. No. 8,493,045 discloses a voltage regulator which is configurable to operate in one of two modes, one of which involves an inductor. To determine whether an inductor is coupled to the voltage regulator, a detection circuit determines whether a regulator output of the voltage regulator resists a change in current driven to the regulator output.